Rotary piston and cylinder devices can take the form of an internal combustion engine, or a pump such as a supercharger or fluid pump, or as an expander such as a steam engine or turbine replacement.
A rotary piston and cylinder device comprises a rotor and a stator, the stator at least partially defining an annular cylinder space, the rotor is in the form of a ring, and the rotor comprising at least one piston which extends from the rotor ring into the annular cylinder space, in use the at least one piston is moved circumferentially through the annular cylinder space on rotation of the rotor relative to the stator, the rotor body being sealed relative to the stator, and the device further comprising cylinder space shutter means which is capable of being moved relative to the stator to a closed position in which the shutter means partitions the annular cylinder space, and to an open position in which the shutter means permits passage of the at least one piston, the cylinder space shutter means comprising a shutter disc.
The term ‘piston’ is used herein in its widest sense to include, where the context admits, a partition capable of moving relative to a cylinder wall, and such partition need not generally be of substantial thickness in the direction of relative movement but can often be in the form of a blade. The partition may be of substantial thickness or may be hollow.
The shutter disc may present a partition which extends substantially radially of the annular cylinder space.
Although in theory the shutter means could be reciprocable, it is preferred to avoid the use of reciprocating components, particularly when high speeds are required, and the shutter means is preferably at least one rotary shutter disc provided with at least one aperture which in the open condition of the shutter means is arranged to be positioned substantially in register with the circumferentially-extending bore of the annular cylinder space to permit passage of the at least one piston through the shutter disc.
The at least one aperture of the shutter is provided substantially radially in the shutter disc.
Preferably the axis of rotation of the rotor is not parallel to the axis of rotation of the shutter disc. Most preferably the axis of rotation of the rotor is substantially orthogonal to the axis of rotation of the shutter disc.
Preferably the piston is so shaped that it will pass through an aperture in the moving shutter means, without balking, as the aperture passes through the annular cylinder space. The piston is preferably shaped so that there is minimal clearance between the piston and the aperture in the shutter means, such that a seal is formed as the piston passes through the aperture. A seal is preferably provided on a leading or trailing surface or edge of the piston. In the case of a compressor a seal could be provided on a leading surface and in the case of an expander a seal could be provided on a trailing surface.
The rotor body is preferably rotatably supported by the stator rather than relying on co-operation between the pistons and the cylinder walls to relatively position the rotor body and stator.
It will be appreciated that a rotary piston and cylinder device is distinct from a conventional reciprocating piston device in which the piston is maintained coaxial with the cylinder by suitable piston rings which give rise to relatively high friction forces.
The rotor ring is preferably rotatably supported by suitable bearing means carried by the stator.
Preferably the stator comprises at least one inlet port and at least one outlet port.
Preferably at least one of the ports is substantially adjacent to the shutter means.
Preferably the ratio of the angular velocity of the rotor to the angular velocity of the shutter disc is 1:1.
We seek to provide a transmission assembly for rotary piston and cylinder devices.